Salt intake is of major importance in cardiovascular disease, particularly hypertension and congestive heart failure. Yet neither doctors nor patients have a convenient way to assess it. As a result, despite its importance, salt intake is rarely monitored. Diet histories are generally very unreliable, and subjects' estimation of their salt intake tends to bear little resemblance to their actual intake.
Currently available methods of estimating salt intake involve measurement of the volume of a collection of a subject's total urine specimens over a 24-hour period and determination of the sodium concentration in the urine collection to allow for calculation of the sodium excretion (i.e. urine volume×sodium concentration). Such urine collections are cumbersome, and offer many obstacles to adequate monitoring of sodium intake. Such obstacles involve delays in obtaining and analyzing the sample, incomplete collection of all urine generated in the 24 hour period of time, inconvenience for repeated or frequent monitoring, and the considerable variation in day-to-day sodium intake. As a result of these obstacles, sodium intake goes largely unmonitored even though routine assessment of sodium intake is of considerable medical importance.